The present invention relates to a vehicle brake rotor and more specifically to a vented brake rotor having tubular vent ducts.
Wheeled vehicles are typically slowed and stopped with a braking system that generates frictional forces. One known braking system is the disc braking system which includes a rotor attached to one or more of the vehicle wheels for rotation therewith. The rotor has an annular peripheral section having a pair of outwardly facing annular friction surfaces also known as the braking surfaces.
The disc brake system also includes a caliper assembly secured to a non-rotating component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake pads, each having a backing plate and brake lining material attached thereto. A pad is disposed adjacent each braking surface such that the brake lining material is adjacent the braking surface. The caliper assembly conventionally includes at least one moveable piston operatively connected to the backing plate of at least one of the brake pads. When the driver brakes the vehicle, hydraulic or pneumatic forces move the piston which clamps the brake lining material of the pads against the braking plates of the rotating rotor. As the pads press against the moving rotor braking surfaces, frictional forces are created which oppose the rotation of the wheels and slow the vehicle.
The friction created by the disc brake system causes the rotor temperature to rise. An excessive temperature rise is undesirable since it may deform the rotor and degrade braking performance.
To improve the performance and wear characteristics of the disc brake system, it is desirable to dissipate the heat generated during braking. Vented rotors dissipate heat using a plurality of air passages formed through the peripheral section. For example, some vented rotors include a peripheral section having a pair of annular braking plates. Spacers, such as posts, connect the braking plates together in a mutually parallel, spaced apart relationship. Radial passages or vents are defined between the braking plates and the spacers. Air circulates through the passages as the rotor turns, passing across the inner surfaces of the braking plates and the surfaces of the spacers. The moving air absorbs the heat and removes it from the rotor as it exits the passages.
The cooling effectiveness of the vented rotor depends in part on the quantity of air moved through the passages. A higher airflow rate through the passages dissipates more heat from the rotor. Therefore, it is desirable to move as much air as possible through the passages as the rotor turns.
It is known that the shape, spacing and orientation of the spacers can affect the airflow rate through the passages. For example, fins may be used as spacers which extend along the inner surfaces of the braking plates to a greater extent than the posts creating shaped passages between the fins. The shape of the passages determines the airflow rate through the passages.
Rotors are commonly manufactured by known casting methods during which the shape and orientation of the spacers are fixed. If a different configuration of spacers and passages is desired, a new rotor had to cast. It is desirable to manufacture a rotor providing more flexibility for determining the shape and configuration of the rotor passages without the need to recast the entire rotor.